Question

Assertion (A): A ray of light travelling in air enters obliquely into a parallel-sided glass slab. The angle of refraction will not be equal to the angle of incidence. 

Reason (R): A ray of light travelling in air enters perpendicularly into a parallel-sided glass slab. The angle of refraction will be equal to the angle of incidencе.

Options

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true but R is not the correct explanation of the assertion.

Explanation:

The assertion is true because light entering obliquely from air to glass changes speed and bends, making the angle of refraction smaller than the angle of incidence. The reason is also true because a perpendicular ray does not bend, meaning both the angle of incidence and refraction are equal to 0°. However, the behaviour of a perpendicular ray does not explain why oblique rays bend.